Inductive rotary transducers are used, for example, to determine the angular position of two machine parts that are rotatable relative to each other. In inductive rotary transducers, excitation windings and receiver coils are applied, for example, in the form of circuit traces, on a shared circuit board, which is permanently connected to a stator of a rotary transducer, for example. Situated across from this circuit board is another board, which generally takes the form of a code disk, on which alternating electrically conductive and nonconductive surfaces are mounted at periodic intervals as a scale-division region or scale-division structure, and which is connected to the rotor of the rotary transducer in a rotatably fixed manner. If an electric excitation field, which is alternating over time, is applied to the excitation windings by applying an excitation current, then signals are generated in the receiver coils during the relative rotation between rotor and stator as a function of the angular position. These signals are processed further in evaluation electronics.
Such rotary transducers are frequently used as measuring devices for electrical drives to determine the absolute angular position of respective drive shafts. In this context, it is important, particularly from the point of view of safety technology, that even after a system shutdown or in the event of a power failure, at least the rotations occurring in this state are counted.
German Published Patent Application No. 197 51 853 describes a construction of an inductive rotary transducer, in which the excitation and receiver coils are arranged in a multilayered circuit board structure.
For such a rotary transducer to be able to count at least the number and direction of the rotations performed even in the event of a failing mains voltage supply, additionally suitable magnets may be provided on the rotor and two magnet sensors on a stator circuit board, which generate counting signals. In this operating state, the magnet sensors are supplied by a buffer battery.